A service brake or brake assembly, such as a disc brake assembly, may include a brake caliper and inboard and outboard brake pads located on opposing sides of a brake rotor. The brake caliper may include one or more brake piston bores, each of which may house a brake piston that moves during a brake apply and during release of a brake apply. During a brake apply to decelerate a vehicle, brake fluid is pressurized, which causes one or more of the brake pistons to move into contact with the inboard brake pad and then move the inboard brake pad into contact with one side of the brake rotor, while an opposing brake pad is moved into contact with the opposing side of the brake rotor.
When a vehicle is already stopped or in a parked position, a parking brake assembly may be used to prevent movement of the vehicle. The parking brake assembly may utilize one or more components of the brake assembly to create a clamping force to prevent movement of the vehicle. During a parking brake apply, the parking brake assembly may cause one or more of the brake pistons of the service brake to move so that the brake pads are moved into contact with the brake rotor to create and maintain the clamping force.
Some vehicles, including passenger cars and trucks, use single brake piston hydraulic brake assemblies for vehicle deceleration. These vehicles may also have a parking brake assembly that utilizes the same single brake piston for creating clamping force to maintain the vehicle in a stopped or parked position. In such parking brake assemblies, an electric motor may generate torque to move the brake piston and therefore the brake pads against the brake rotor to create the parking brake force.
Other vehicle platforms, like full-size trucks, vans, and SUVs, use multi-brake piston brake assemblies for vehicle deceleration only, and a separate parking brake assembly for maintaining the vehicle in a parked position.
To improve parking brake performance, while also reducing weight, costs, and packaging space, in some vehicle platforms such as full-size trucks, vans, and SUVs, it may be desirable to have a parking brake assembly that utilizes an existing multi-brake piston brake assembly. It may be desirable to have a parking brake assembly that utilizes an existing multi-brake piston brake assembly without requiring a super high output motor to move the brake pistons and the brake pads against the brake rotor to create the clamping force. For example, it may be attractive to have a parking brake assembly for a heavy-duty vehicle platform with a multi-brake piston brake assembly that can use a motor from a light-duty vehicle platform to sufficiently move the brake pistons and brake pads against a brake rotor to create sufficient clamping force.